Is Häagen-Dazs ice cream as addictive as heroin? Or, put another way, is heroin as addictive as Häagen-Dazs?

Depending on how you phrase the question, you’re either asking whether heroin addiction is no more serious than a love of junk food, or you’re questioning whether junk food junkies may have a serious disorder that needs intervention. Now a new study suggests that there may be no clear, bright line between addictive and normal responses—and adds to the evidence that all “addictions” act on the same motivational system in the brain.

The study, published Monday in the Archives of General Psychiatry, involved 39 healthy women, who ranged in weight from lean to overweight or obese. The participants were asked to complete the Yale Food Addiction Scale, which tests for signs of food addiction. Women with full-fledged eating disorders of any type were not included in the study.

Then, using fMRI, researchers led by Yale’s Ashley Gearhardt and Kelly Brownell looked at the women’s brain activity in response to food. In one task, the women were asked to look at pictures of either a luscious chocolate shake or a bland, no-calorie solution. For another brain-scan task, women actually drank the shake — made with four scoops of vanilla Häagen-Dazs ice cream, 2% milk and 2 tablespoons of Hershey’s chocolate syrup — or the no-calorie control solution, which was designed to be as flavorless as possible (water couldn’t be used because it actually activates taste receptors).

The scientists found that when viewing images of ice cream, the women who had three or more symptoms of food addiction — things like frequently worrying about overeating, eating to the point of feeling sick and difficulty functioning due to attempts to control overeating or overeating itself — showed more brain activity in regions involved with pleasure and craving than women who had one or no such symptoms.

These areas included the amygdala, anterior cingulate cortex and medial orbitofrontal cortex — the same regions that light up in drug addicts who are shown images of drug paraphernalia or drugs.

Similar to people suffering from substance abuse, the food-addicted participants also showed reduced activity in brain regions involved with self-control (the lateral orbitofrontal cortex), when they actually ate the ice cream.

In other words, women with symptoms of food addiction had higher expectations that a chocolate shake would be yummy and pleasurable when they anticipated eating it, and they were less able to stop eating it once they started.

Interestingly, however, unlike drug addicts, the participants with more signs of food addiction did not show a decrease in activity in pleasure-related regions of the brain when they actually ate the ice cream. People with drug addictions tend to derive less and less pleasure from drug use over time — they want drugs more but enjoy them less, creating compulsive behavior. But it’s possible that this tolerance may be seen only in serious addictions, not in people with just a few symptoms.

Notably, the study also found that food addiction symptoms and brain responses to food were not associated with weight: there were some overweight women who showed no food addiction symptoms, and some normal-weight women who did.

That’s why addictions aren’t simple: they involve variations not only in levels of desire, but also in levels of ability to control that desire. And these factors may change in relation to social situations and stress.

Neither heroin nor Häagen-Dazs leads to addiction in the majority of users, and yet there are certain situations that may prompt binges in people who otherwise have high levels of self-control. So the answers to addiction may lie not in the substances themselves, but in the relationship people have with them and the settings in which they are consumed.